Heart attacks are a leading cause of death in the industrialized world. Many heart attacks are caused in part by narrowed, stenosed coronary blood vessels. One medical procedure commonly used to deal with coronary vessel stenosis is angioplasty. Angioplasty, in particular Percutaneous Transluminal Coronary Angioplasty (PTCA), involves inserting a balloon catheter into the femoral artery near the groin, and advancing the catheter over the aortic arch and into a coronary artery. The balloon can be advanced through the coronary artery to the stenosis and inflated to widen or dilate the narrowed region. The balloon catheter can then be withdrawn. In some cases, the widened coronary vessel rebounds or re-closes, narrowing the vessel again over a period of time.
Intraluminal prostheses, such as a stent, graft, patch, or the like, are increasingly used to prevent the widened vessel regions from narrowing again after angioplasty. An intraluminal prosthesis, typically having a tubular shape, can be put in place in the widened vessel region to hold the vessel walls apart and the lumen of the vessel open in the event the vessel attempts to narrow again. One class of intraluminal prostheses requires that the intraluminal prosthesis be forcibly outwardly expanded, such as with a balloon catheter, to place the intraluminal prosthesis into position against the vessel walls. Another class of intraluminal prostheses, self-expanding intraluminal prostheses, can be delivered to a site in a compressed or constrained configuration and released in the vessel region to be supported. The self-expanding intraluminal prosthesis then expands in place to a configuration having a wide lumen, typically pressing firmly against the vessel walls where released. Self-expanding intraluminal prostheses are often elastically biased to assume an original larger shape after being temporarily compressed into a smaller size to more easily be transported through blood vessels to the target site. The intraluminal prosthesis is commonly placed at a recently dilated, stenosed vessel region.
Self-expanding intraluminal prostheses can be delivered to a target site via catheter, mounted over an inner tube or shaft and constrained within the distal end of an enclosing retractable tube or sleeve. The self-expanding intraluminal prosthesis can be freed from the restraint of the outer sheath by either distally pushing the inner shaft against the intraluminal prosthesis or proximally pulling the retractable outer sheath from over the intraluminal prosthesis. The release of the self-expanding intraluminal prosthesis must be done carefully to avoid tearing the intraluminal prosthesis or dragging the intraluminal prosthesis out of the desired position by the movement of the outer sheath. Once free of the restraint of the outer sheath, the self-expanding intraluminal prosthesis can expand to force itself against the vessel inner walls.
In general, a catheter should have a maximum radial extent or profile no larger than necessary, in part to enable the catheter to reach further into narrower vessel regions. The desired size of the intraluminal prosthesis to be delivered may not be known until the patient is in the operating or treatment room of a hospital. Therefore, many surgeons must choose an appropriately-sized intraluminal prosthesis and load it onto the catheter by hand while the patient is anesthesized. A self-expanding intraluminal prosthesis is most easily loaded in a proximal direction onto a catheter by compressing the intraluminal prosthesis and sliding the intraluminal prosthesis co-axially over the inner shaft distal end and within the retractable outer sheath. The intraluminal prosthesis must thus typically be slid over the catheter distal tip. The distal tip is optimally tapered into a nose cone having a proximal width about the same as the width of the outer sheath, to provide a smooth transition from the distal tip to the outer sheath. This can present a situation where the compressed intraluminal prosthesis has an inner diameter too small to be advanced over the larger outer diameter nose cone of the catheter. Even if the size of the compressed intraluminal prosthesis is chosen for loading over the nose cone, this process is very inefficient and may result in damage to the intraluminal prosthesis or adverse effects to the patient due to the increased time needed for the operation.
Moreover, intraluminal prostheses with a material lining the inside, outside, or both may present even more challenges for loading and delivery, particularly if the material is biological and its viability must be preserved.
It is known to crimp the intraluminal prosthesis onto the delivery catheter just prior to the implantation procedure. This was carried out manually in the operating room and could result in asymmetrical, uneven, or incomplete crimping. It was recognized that hand-crimping resulted in a nonoptimal catheter/intraluminal prosthesis assembly and commercial suppliers began to provide pre-crimped intraluminal prosthesis/catheter kits. At the present, such prepared assemblies are in standard use for many types of intraluminal prosthesis delivery procedures. However, there are myriad combinations of intraluminal prosthesis diameter, intraluminal prosthesis length, intraluminal prosthesis material, intraluminal prosthesis configuration, catheter diameter, catheter length, and other variables which might be desired for many various procedures. It can be expensive and wasteful of time and space for a hospital to stock the wide selection of intraluminal prosthesis/catheter kits which might be needed across the spectrum of surgical intraluminal prosthesis procedures and patient types/sizes. Even if the necessary catheter size and intraluminal prosthesis type can be estimated before the procedure to narrow down the universe of possible intraluminal prosthesis/catheter kits which might be needed, the intraluminal prosthesis size may need to be determined during the procedure. A variety of intraluminal prosthesis/catheter kits, therefore, still must be made available in the operating room.
Accordingly, it is desirable to provide a method and apparatus of an intraluminal prosthesis delivery apparatus which avoids damage to the intraluminal prosthesis, allows surgeons to select an intraluminal prosthesis without regard to compressed size, and provides a modular system for efficiency and economy in storage and selection.